4L60E loosing Fluid. But not on the ground HELP!

Alright heres the issue. I put a quart of tranny fluid into my truck yesterday. And it had a flush recently so i wasnt to concerned. Well after a 20 miles drive i had to put in another Quart of ATF... I wasnt happy and still didnt think that much of it. Today I went out and checked it after running to my buddies house last night (about 5 miles total). Today i was over 1 1/2 quarts down again.
I am not leaking it onto the ground. It isnt in my coolant. and my transfercase isnt pouring it out onto the ground yet either. But that is where i think it is going. I think the seal let loose and is allowing the fluid into the transfer??
I know that the 4L80E that the hummer has for the military has a cooler that runs thru the transfer and will break allowing tranny fluid in that way. I am just not sure if my truck has the same type of cooler or if i just have a bad output seal? any help and input would be awsome since i kinda need to get this done. Oh and as a last note i have not had a chance to check the transfercase fluid level but i am not driving the truck till i get this figured out.

Well i think i found the culprit.. a bad output shaft seal going from the tranny to the transfer.. It will be going into the shop on monday since i dont have time to do the work myself.. Unless i get up early (fat chance) and tear into it.